Unsolicited redesigns are tough: they often miss valuable context and critical constraints, or they ignore business goals completely. But sometimes, just sometimes, the unsolicited redesign will strike on something better and true.
I can't say for certain that Flatstudio has achieved this with their unsolicited redesign of the entire Google Play store, but there's no doubt that they've touched upon a beautifully-executed design system for every kind of media Google sells. From a visual perspective, the imagery and color theming work wonders – I immediately went to the production Google Play Store and was hoping to see something equally as rich. Flatstudio is far, far ahead – at least in the visual dimension.
Regardless: Flatstudio has built an interesting case study with a fun, interactive demo website. I can't imagine how many hours went into this, but I'm glad it's live for all of us to admire.